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1,4-Butanediol (1,4-BDO) is a valuable industrial chemical that is primarily produced via several energy-intensive petrochemical processes based on fossil-based raw materials, leading to issues related to: non-renewability, environmental contamination, and high production costs. 1,4-BDO is used in many chemical reactions to develop a variety of useful, valuable products, such as: polyurethane, Spandex intermediates, and polyvinyl pyrrolidone (PVP), a water-soluble polymer with numerous personal care and pharmaceutical uses. In recent years, to satisfy the growing need for 1,4-BDO, there has been a major shift in focus to sustainable bioproduction via microorganisms using: recombinant strains, metabolic engineering, synthetic biology, enzyme engineering, bioinformatics, and artificial intelligence-guided algorithms. This article discusses the current status of the development of: various chemical and biological production techniques for 1,4-BDO, advances in biological pathways for 1,4-BDO biosynthesis, prospects for future production strategies, and the difficulties associated with environmentally friendly and bio-based commercial production strategies. [ABSTRACT FROM AUTHOR]

Violacein is a pigment synthesized by Gram-negative bacteria such as Chromobacterium violaceum. It has garnered significant interest owing to its unique physiological and biological activities along with its synergistic effects with various antibiotics. In addition to C. violaceum, several microorganisms, including: Duganella sp., Pseudoalteromonas sp., Iodobacter sp., and Massilia sp., are known to produce violacein. Along with the identification of violacein-producing strains, the genetic regulation, quorum sensing mechanism, and sequence of the vio-operon involved in the biosynthesis of violacein have been elucidated. From an engineering perspective, the heterologous production of violacein using the genetically engineered Escherichia coli or Citrobacter freundii host has also been attempted. Genetic engineering of host cells involves the heterologous expression of genes involved in the vio operon and the optimization of metabolic pathways and gene regulation. Further, the crystallography of VioD and VioE was revealed, and mass production by enzyme engineering has been accelerated. In this review, we highlight the biologically assisted end-use applications of violacein (such as functional fabric development, nanoparticles, functional polymer composites, and sunscreen ingredients) and violacein activation mechanisms, production strains, and the results of mass production with engineered methods. The prospects for violacein research and engineering applications have also been discussed. [ABSTRACT FROM AUTHOR]